AAGBI recommendations for standards of monitoring during anaesthesia and recovery 2015 – a further example of ‘aggregation of marginal gains’

When these authors first started anaesthetic training, the concept of AAGBI minimal monitoring was still in the future. The state-of-the-art monitors of the time, pulse oximeters and capnograms, were in short supply, a single device normally being shared between several theatres and so rarely available to the novices. Since their first publication in 1988, the AAGBI recommendations have become globally accepted as a baseline standard for monitoring to which all anaesthetists should work. In recent years, this drive to raise standards of monitoring has evolved to also include resource-poor countries through the Lifebox charity (www.lifebox.org), aiming to ensure all patients who have a general anaesthetic (GA) anywhere in the world receive at least pulse oximetry 1. This month sees the publication of the 5th edition of the ‘Recommendations for standards of monitoring during anaesthesia and recovery’ by a working party of experts assembled by the AAGBI 2. The most significant change, based on its potential impact on anaesthetic departments, is the new requirement for continuous monitoring, including airway pressure, airway gases and vapours, temperature and neuromuscular function. ‘Continuous’ is not defined, but based on the American Society of Anesthesiology monitoring guidelines 3, means ‘prolonged without any interruption at any time’. While few clinicians would dispute the need to monitor these variables while transferring a patient around the hospital, or for anaesthetised patients located in the emergency department or recovery, the new AAGBI recommendation places particular emphasis on the transfer between theatre and recovery, though stops short of commenting on discontinuing monitoring between the UK's beloved anaesthetic room and theatre. Is it necessary to maintain this level of monitoring on the journey to recovery? This will clearly depend on the distance involved and condition of the patient, but neuromuscular function and temperature are unlikely to change significantly for the worse during this time. The value of monitoring inspired oxygen and expired carbon dioxide during brief transfers is more difficult to assess. In a previous AAGBI safety statement 4, the rationale for using capnography outside of the operating theatre related to demonstrating effective cardiopulmonary resuscitation or displacement of tracheal tubes out of the airway during patient movement and transport, presumably therefore in ventilator-dependent patients. Transferring a spontaneously breathing patient, most commonly breathing through their own airway or via a supraglottic airway, using a breathing system that cannot deliver less oxygen than in air, with a trained anaesthesia provider observing them, is not comparable to an intubated, ventilated patient. Similarly, a continued blanket recommendation that all patients should receive supplemental oxygen during recovery from surgery is disappointing when pulse oximetry is now ubiquitous and oxygen therapy is now recommended to be targeted to a predefined oxygen saturation in most situations where oxygenation is threatened 5. This is exemplified in our unit where increasing numbers of oncology patients have received bleomycin therapy, and routine administration of oxygen in these patients would be detrimental. Recommended monitoring of patient temperature has changed from having a means of measuring temperature available to forming part of the minimal monitoring for both the intra-operative and recovery phases, including outside the operating suite. This standard is compatible with National Institute for Health and Care Excellence (NICE) guidance 6, which also recommends monitoring temperature in all patients having general, regional or combined anaesthesia, irrespective of their risk of inadvertent peri-operative hypothermia. Despite the NICE guidance being published seven years ago, intra-operative temperature monitoring is not yet universal. It is rarely performed intra-operatively in patients having regional anaesthesia, and those having short GAs of less than 30 minutes duration, this being the NICE recommended duration between measurements 6. In these patient groups, some degree of hypothermia still occurs due to central to peripheral body-heat redistribution, and only pre-warming can attenuate this, there being insufficient time to correct the hypothermia using standard warming techniques 7. This situation illustrates the problem of applying ‘minimal’ requirements to all patients rather than allowing a more focused approach to patients based on their individual requirements, and may encourage clinicians to use monitors unnecessarily, exposing the patient to the risk of complications (e.g. epistaxis following insertion of a nasal temperature probe) and the healthcare provider to extra cost. The recommended level of monitoring of patients who receive neuromuscular blocking drugs (NMBs) has been increased from having a nerve stimulator available to mandatory monitoring for all patients receiving NMBs from induction until recovery. The limitations of subjective tactile or visual methods of assessing neuromuscular block are also highlighted, and departments are encouraged to move to quantitative forms of NMB monitoring, which is a major component of a recent call for a more strategic approach to their use 8. This will be a significant change to current practice in most UK hospitals, with cost implications, but is timely considering recent research highlighting the contribution of NMBs to both awareness 9 and postoperative pulmonary complications 10. A recommendation to monitor cuff pressures in both tracheal tubes and supraglottic airways is new and, for the latter devices, overdue 11. However, the evidence base for the recommendation in the case of tracheal tubes is not provided, mostly because a majority of research in this area concerns intensive care patients and avoidance of ventilator-associated pneumonia 12, rather than intra-operative use. Despite this, any document that helps to discredit the still widely-held belief that digital palpation of the pilot balloon serves a useful purpose is to be applauded 13. Monitoring of end-tidal carbon dioxide is now recommended for patients receiving sedation. This is widespread practice, with some support in the literature 14, and involves using purpose-made face masks or nasal cannulae, or various Heath Robinson systems of inserting the capnogram sampling tube into the side of a face mask. The sampled gas arriving at the capnogram will contain mostly room air, sometimes contaminated with carbon dioxide from the patients' expired breath, hopefully in large enough amounts to monitor the existence of breathing and so the respiratory rate. An inexperienced clinician with only a superficial grasp of physiology and capnography may be tempted to believe that the end-tidal reading displayed is an indicator of the adequacy of respiration. This is a hazardous misconception as the mix of expired gas, room air, and sometimes additionally administered oxygen, will be highly variable depending on the oxygen flow rate, route of breathing (oral or nasal), tidal volume and respiratory pattern, in particular the peak expiratory flow rate. This monitoring should therefore be regarded only as an apnoea alarm with a high false positive rate, and if it is to be recommended as mandatory monitoring it would have been useful to highlight its limitations, including avoiding the term ‘end-tidal’. Transcutaneous carbon dioxide monitoring is feasible in sedated patients 15, and might provide more useful information about the adequacy of respiration, but would still be a rather late indicator of apnoea. It is now recommended that audible monitoring alarms are activated before anaesthesia commences, rather than simply during anaesthesia. This minor change seems sensible as a way of warning the clinician of the commonly-occurring physiological abnormalities at induction, when he or she may be distracted while performing other procedures such as regional blocks or vascular access. However, the last few seconds before unconsciousness is stressful for patients, and being surrounded by a cacophony of alarms does not represent an ideal patient-centred induction, particularly if the alarms are ignored by staff who know they are normally of little import 16. When complying with these recommendations, we would suggest careful setting of alarm limits (as described in the AAGBI guidance) for this turbulent period of any GA to avoid exacerbating already high patient-anxiety levels 12. So how might anaesthetic departments fare when implementing these new recommendations? For our large department, the cost of purchasing new quantitative peripheral nerve stimulators and portable gas monitors for the 70 sites where anaesthesia is delivered will be substantial. Justifying the cost in terms of improved patient outcomes will be challenging, perhaps more so for the portable gas monitors than for the nerve stimulators. Within the UK, the drivers and enablers for purchase of equipment have taken unexpected turns. The challenging financial environment has made it hard for departments to secure funding as purchasers have focused on economic advantages of new equipment to the detriment of clinical evolution. In the face of this austerity, clinicians have found allies in national bodies such as NICE, whose recommendations carry far greater currency than departmental requests. For example, the 2002 NICE recommendation that ultrasound should be used routinely for insertion of central venous catheters saw a rapid expansion in the availability of ultrasound machines, which would have been impossible without that document. As well as the anticipated increase in use of ultrasound for central venous cannulation, there was also a parallel leap in clinical quality with a dramatic surge in the use of the same devices for regional anaesthetic techniques. Similarly, NICE guidance on cardiac output monitoring was used to inform the National Technology Assessment Centre guidance on intra-operative fluid management. Local compliance with this guidance was driven through the Commissioning for Quality and Innovation (CQUIN) framework, whereby payments were linked to the use of fluid management monitoring technology for high-risk patients 17. This afforded clinicians the leverage they required to purchase monitoring equipment that would have been difficult for them to obtain otherwise. This system saw the drivers come full circle from clinicians clamouring for equipment on clinical grounds, to one where use by clinicians was mandatory to ensure payment. Other drivers of change in clinical practice are also beginning to emerge, for example the Royal College of Anaesthetists Anaesthesia Clinical Services Accreditation scheme. It is in this new environment, alongside other influential big hitters, that the AAGBI document must find a place. Whatever the intended role, it is difficult for these other single documents to satisfy all of these. If they are standards for audit and accreditation, or as a medicolegal standard, then their lack of detail sets a low bar. Where they are perhaps most useful is as a standard for clinicians to persuade those who hold the purse strings that investment in monitoring is required. Although the new AAGBI document is more detailed, conciliatory phrases such as ‘departments should work towards’ and ‘departments are encouraged’ leave open the option of inactivity and are unlikely to carry sufficient influence. If the document is intended to be a comprehensive manual of monitoring, then it lacks the detail required to encompass every clinical scenario. Rather than focusing on ‘minimal’ monitoring standards it could instead have described ‘principles of recommended monitoring’ or have been taken even further to represent a ‘gold standard’ for what monitoring must be used in what clinical situations. It could then present practical detail on the required monitoring and a thorough critical appraisal of the evidence for those recommendations. Despite these reservations, we believe this document will continue to be a fundamental component in improving the safety of anaesthesia. But this is becoming a progressively more difficult task 21, and refining monitoring to improve safety probably now falls within the concept of ‘aggregation of marginal gains’. Explaining the unprecedented success of his team at the 2012 Olympics, British Cycling's performance director David Brailsford said ‘the whole principle came from the idea that if you broke down everything you could think of that goes into riding a bike, and then improved it by 1%, you will get a significant increase when you put them all together’ 22, 23. Hopefully, if the recommended numerous small modifications to our routine monitoring are enthusiastically and fully adopted, we will achieve an equivalent outcome for our patients. No external funding and no competing interests declared.